First Premise: Those who support more than a minimalist government (the Statists who believe the government represents the culture) are constantly in search of ways to lock in the power of government against the possibility that it might be reduced. By using regulations, better expressed simply as controls, we are constantly forced to toe the line in some new manner. Those who support only the level of government required to protect the citizens in the ways they can't protect themselves, are the individualists. The US Constitution was written by and for individualists, but it has been moved inexorably towards statism in many ways by the Federal Courts which have the duty of interpreting it.
Along the way to developing the culture, the idea of Civil Rights was born. Those rights are defined generally as human rights, and some of them are explicitly enumerated in the Bill of Rights to the Federal Constitution (and copied by most State constitutions as well).
Second Premise: Civil Rights are where the rubber meets the road in the interpretation of the Constitution. The Statist progenitors of a more pervasive and controlling central Government appoint the Judges who have to interpret the Constitution, so it follows that these men and women of power and authority would spread the idea of larger and more pervasive government with their rulings, and they do.
The First Amendment to the Constitution, a strong Civil Right, started simply enough, as a mandate to allow individual freedom of expression and association, but it has since changed via interpretation so radically that it was recently used to allow large, well-financed groups to effectively buy elections, which is a terrible perversion of the purpose of the First Amendment. Since the First Amendment doesn't directly oppose the Federal Government, and as seen in my example, can be twisted to suport statism, it is not often opposed by the statists.
The Second Amendment to the Constitution, the right to keep and bear arms, was inserted into the Bill of Rights by the Founders for the stated purpose of allowing the arming of militias, or armed forces of the People, to exist as a check on the power of the Federal Government, which the Founders refused to trust for the maintenance of individual freedoms (the Founders were assuredly NOT statists). The Second Amendment was written as, and is currently interpreted as, a Civil Right, as it upholds the basic Human Right of self-defense of one's life. As written and interpreted, it stands as an absolute limit on the power of the Federal Government. If the Federal Government assumes (seizes) too much power from the People, the Founders expected that militias would be formed of adequately-armed men to oppose, and if necessary, remove the Federal Government (restore the "Free State"). Since the Second Amendment puts a (unstated, sadly) limit on Government power and control, it is considered undesireable by statists, and is opposed.
That's it, readers. it's really this simple. Statists, currently represented by most politicians of both major parties, believe that bigger government is better, and they have been working towards that goal for several generations now. They work towards that goal by supporting implementation of rules which support them, and by fighting against rules which work against them. The Second Amendment works against Statists, so it will always be opposed. The way we see it being opposed now is highly opportunistic, but the opportunism we see is only part of the greater opposition of this core Civil Right which envisions the use of force to maintain individual freedoms.
Now you know why the fight to maintain the 2A is a constant fight which will never end and must never end.
The day the right to keep and bear arms ends by fiat of the Federal Government, the Republic ends. At that point, we either end it in an appropriate use of our Second Amendment right, or we end the Republic by agreeing that it's time is done and it's Constitution is irrelevant. One of those two things will happen upon the death of the Second Amendment.
BTW, Readers, the entire Bill of Rights, under which umbrella this libertine culture of ours has flourished, ends the same day as the Second Amendment ends, and the entire direction, life and force of the culture then exists only at the whim of the Government. Ask yourself if YOU want to surrender every single choice you get to make to this, or any other, Government. If you do NOT choose surrender, then you'd better possess, maintain and be practiced with the arms that the Second Amendment now permits, and you'd better be prepared to fight with those arms.
H/T for the inspiration of my muse goes to the Country Gal, who has reminded me to stay on task.